The goal of this project is to develop the first high efficiency, continuous system for conversion of liquid-phase samples to gas-phase samples for application in C-14 biomedical accelerator mass spectrometry. Analysis of biological samples using AMS is currently hampered by the inability of the instruments to accept liquid-phase samples directly, and in particular the inability to accept samples eluted from conventional separation systems such as HPLC. The proposed system accomplishes liquid-phase sample analysis through a process of evaporative separation of analytes from solvent followed by catalyzed combustion of sample carbon to carbon dioxide to facilitate transport into the AMS ion source. A unique feature of the system is site-specific heating of samples on a catalyst bed with continuously directed laser irradiation of effect combustion of sample carbon in a highly selective and controlled fashion. The system preserves the resolution of samples deposited on the catalyst bed. This system will be coupled to a compact biomedical AMS developed by NSI to demonstrate, for the first time, continuous detection of labeled molecules from an HPLC using an AMS. It will also be suitable for use with other existing AMS systems. PROPOSED COMMERCIAL APPLICATION: The laser-induced sample conversion (LISC) system will have widespread commercial applications in biomedical AMS research in toxicology, drug development, and associated 14C tracer studies. The cost and size of a combined LISC-AMS system will be compatible with installation at major medical research centers. The LISC system will also have a commercial market as a stand-alone product that will facilitate biomedical applications of any existing AMS system.